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Occidental Chemical Cori .3tion <br /> Summary 2006 Annual Review Meeting Minutes 1 <br /> and Semi-Annual Report <br /> Lathrop, CA - 4 - 23 October 2006 <br /> they will install a dissolved oxygen (D.O.) sensor that sends a notification alarm to CRA <br /> personnel if the D.O. levels fall below a certain threshold. Please provide the D.O. <br /> sensor installation status in the next Annual Groundwater Remedial Program Report. <br /> 6. The Regional Board staff asked MSRM why they sampled the City of Lathrop's well for <br /> organochlorine (OC) and organophosphorus (OP) pesticides. MSRM stated that the <br /> sampling of those compounds is corporate policy to ensure that MSRM know of any <br /> compounds that could potentially be found in municipal drinking water wells that are <br /> located in the vicinity of their groundwater remedial systems. The Regional Board staff <br /> then asked why these compounds were not sampled in the influent and/or effluent of <br /> the treatment system. MSRM indicated that the permanent wells have historically <br /> shown little to no detectable OC and OP compounds. Although some benzene <br /> hexachloride (BHC) isomers were detected, the sampling for OC and OP in on-site <br /> wells was discontinued in the revised 2004 Monitoring and Reporting Program (MRP). <br /> The Regional Water Board staff is satisfied by this response. <br /> 7. The Regional Water Board staff discussed the need to evaluate inorganic compounds <br /> (nitrate, sulfate and chloride) in the upper aquifer and compare them to those in the <br /> aquifer beneath the Corcoran clay layer due to the site's past operations as a fertilizer <br /> plant. The Regional Board staff requests MSRM add the inorganic compounds to the <br /> annual sampling regime of the aquifer beneath the Corcoran Clay layer. These <br /> additional monitoring requirements will also be included in the next revised MRP. <br /> 8. The Regional Water Board staff requested that MSRM conduct regular public <br /> participation meetings. In addition, MSRM should prepare an updated remedial <br /> program fact sheet that must be mailed to residents, tenants and property owners <br /> overlying and within 1,000 feet of the groundwater plume. The Regional Water Board <br /> staff concurred that the remedial system website (www.lathropsite.com) should be <br /> updated to include current status of groundwater impacts, system performance, any <br /> plans for future system optimization and a schedule for regular public participation <br /> meetings. The Regional Water Board staff will assist and participate in public <br /> participation meetings and must review fact sheets before finalization and mail-outs. <br /> Updates to the website can be discussed in the Semi-Annual Reports prepared for the <br /> site. <br /> Semi-Annual Report, June 2006 <br /> The Regional Water Board staff has the following comments on the Semi-Annual Report <br /> dated 15 August 2006: <br /> 1. Based on our review of the recent semi-annual groundwater analytical data from the <br /> groundwater zones above the Corcoran clay layer and the fact that past OCC activities <br /> handled and/or produced fertilizers on site, the Regional Water Board staff request that <br /> the annual groundwater sampling program be modified to include sampling for total <br /> dissolved solids (TDS) in wells PW04-113, PW09-123, PW12-139 and PW22-164 and <br /> TDS, nitrate, sulfate and chloride in wells PW09-338, PW12-315, PW16-329 and <br />